The process of vaccinating eggs is important in the medical field and in poultry production. In medicine, eggs are used to incubate biological material utilized in the production of vaccines. In poultry production, the objective of in-egg vaccination is to protect the animals from endemic diseases.
Embryos receiving vaccine three days before hatching instead of the first day after hatching have more time to develop antibodies and consequently have a greater resistance to diseases. In this process, the vaccine ideally is applied directly into the amniotic fluid cavity of the egg, without penetration of the embryo. The incubation time for a chicken embryo is 21 days, and in-egg vaccination is normally performed three days prior to hatching, during the routine process of transferring the eggs from the incubator machine to the hatcher machine. The eggs that have previously been secured in incubator trays in which the eggs are fixed in a vertical position with the wider end of the egg up are now transferred in sets of one to four “flats” (trays) into hatcher baskets, where they are allowed to lay down in unencumbered positions so that they can hatch without injury.
The egg is composed of a shell, a membrane adhering to the inside of the shell, an interior membrane holding the embryo within the amniotic fluid, and an area between the two membranes holding the allantoidal fluid. As the egg is incubated, the outer membrane gradually separates from the shell, creating an air cell. This air cell is located in the top of the egg as per its position in the incubator tray. The process of vaccinating in-egg must be done with care to avoid cracking the egg shell or penetrating the embryo, either of which can be fatal to the embryo.
To distribute the vaccine to the injectors, the technology-taught by U.S. Pat. No. 6,240,877 utilizes a sealed pressurized air chamber constructed of rigid acrylic within which air pressure is applied to a collapsible plastic vaccine bag suspended within the chamber, forcing the liquid vaccine from the bag into the distribution system. The chamber is composed of a rigid acrylic chamber that is secured into a base plate, forming a tight seal. One or more vaccine bags are placed on a holder within the chamber that supports the bag in an upright position and flexible tubing is connected to an adapter on the bottom of the bag. The flexible tubing passes through a sealed “O” ring in the base of the chamber. This tubing is the vaccine distribution line and is connected to a distribution manifold that distributes the vaccine to the injectors. Compressed air is fed into the chamber and the vaccine bag is put under pressure in order to force the vaccine to the injectors. The injectors are opened and closed in a timed operation to deliver vaccine to the eggs.
A major problem with the device taught by the '877 patent is safety. The rigid acrylic chamber is kept constantly under pressure from compressed air. This pressure places strain on the internal surface area of the chamber, and as the stress of usage progresses the plastic begins to weaken. Furthermore, any mishandling of the chamber during cleaning or storage can cause fractures which might not be apparent to the operator. If this chamber should rupture while under pressure, shredded pieces of plastic could cause injury to the operators. Another serious problem with the device taught by the '877 patent could occur in the course of the routine working day when replacing the used vaccine bag for a new bag full of vaccine. To change the vaccine bag it is necessary to first remove all pressure from the chamber. If an inattentive employee does not drain the pressure before removing the chamber, the chamber would be forced off the base with an explosive pressure that could cause serious injury.
There is also a problem with the accuracy of vaccine dosage in the device taught by the '877 patent. To distribute vaccine into the vaccination system, the compressed air exerts pressure on the vaccine bag, forcing the vaccine into the flexible tubing leading to the vaccine distribution manifold. From the distribution manifold, the vaccine continues on to the individual injectors that receive a timed amount of vaccine. A problem occurs because of fluctuations in the pressure being exerted on the vaccine bag in the pressure chamber. This pressure is read and corrected within the chamber. However, the causes of the change in pressure occur at the individual needles where the vaccine is injected. When the needles puncture the eggs and the vaccine begins to be injected, there is an immediate drop in pressure in the vaccine line which influences how much vaccine flows through the line. The response to that pressure drop will only begin to occur when the pressure change reaches the chamber where the pressure sensor reads the drop and then more air pressure is applied. By that time, the injection process will have been completed and while more air pressure is being applied within the chamber, the vaccine lines are closed and pressure within the lines is increasing. In other words, by measuring the pressure in the pressure chamber at the farthest point from where the line opens and closes to deliver vaccine, the pressure control system is always working to compensate for changes that have already occurred, and this affects vaccine dosage. It can also affect the quality of the vaccine, which is pressure sensitive. If the pressure on the vaccine goes above 5 psi it can damage and perhaps crush the vaccine cells. Since the pressure in the device taught by the '877 patent is measured and controlled in the chamber, there are no direct controls on the pressure in the vaccine line. In fact, the pressure in the line is not known. Even though the pressure is maintained at a safe level in the chamber, it is possible that at the ends of the vaccine lines, the pressure can rise above that safe pressure level.
Finally, the device taught by the '877 patent has no automatic turn-off system when the vaccine bags are empty. If the operator does not notice that the vaccine bags are empty, the vaccinator continues to operate without injecting vaccine.
The current technology for a platform securing injectors over eggs to be injected is taught by U.S. Pat. No. 5,136,979. The device taught by the '979 patent utilizes a platform composed of two plates, a stabilizer plate and a tooling plate, which are attached together so that they raise and lower as one unit, with aligned holes in each through which injectors are guided. The plates are fixed to air cylinders that raise and lower the plates by the addition or subtraction of air. These air cylinders are secured to the vaccinator body. The entire tooling/stabilizer platform unit with injectors rests on the air cylinders that raise and lower the unit over flats of eggs so that when in movement, the plates and injectors are being propelled and supported by columns of air. In the resting position, the injectors are supported on the lower tooling plate. When the injectors are in position for injection, a narrow bladder located in the upper stabilizer plate is inflated with fluid to secure the superior portion of the injectors in place. Shell punches to open the egg and needles to deliver the vaccine within those punches are located within the injectors, and are driven from the injectors by compressed air.
In the device taught by the '979 patent, the tooling/stabilizer plates lower the injectors over the eggs to be vaccinated until the injectors make contact with the eggs. In the process of settling on the eggs, the injectors are raised slightly above the stabilizer plate and then the injectors are secured in position by the inflation of the narrow fluid bladder located in the upper stabilizer plate, which is the plate farther away from the eggs and therefore in a less firm position for securing the injectors. The tooling/stabilizer plates are suspended from the body of the vaccinator by columns of air within the air cylinders. There are no brake locks on the plates to secure them in position. During the vaccination process, subtle vibrations are created in the plates that can cause cracks in the eggs. These vibrations are caused when there is a change in the equilibrium between the force of the injector propelling the punch and needle into the eggs and the force of the air pressure in the air cylinders securing the plates over the eggs. At the moment when the punch makes contact with the eggshell, the injectors are forced upward slightly, causing the air in the cylinders securing the plates to compress. The sudden impact of the eggshell being penetrated causes disequilibrium between the downward force of the injectors and the upper force of the air cylinders, causing a slight rise in the tooling/stabilizer plates causing a vibration that is transferred to the eggs. After penetration, there is an inverse downward pressure on the eggs until equilibrium is reached. This vibration can be harmful to the eggs, causing an uneven force of penetration and possibly cracks to the eggs when the plates come down after the air pressure in the injection device has been released.
In addition, the device taught by the '979 patent has a narrow fluid bladder located in the superior stabilizer portion of the stabilizer plate and a tooling plate that secures the injector once it is in contact with the egg. Because the bladder secures only the very top portion of the injector at the point most distant from the egg, there remains the possibility for lateral movement of the lower part of the injector when the punch and needle make contact with the egg, which can cause hairline cracks on the eggshell. These cracks can induce a loss of fluids from the egg and cause embryonic death. The further the fluid bladder securing the injector is from the point of contact with the egg, the greater the possibility of lateral movement, and the greater that lateral movement can be.
Furthermore, the device taught by the '979 patent utilizes a stabilizer plate and a tooling plate platform to support injectors in their proper orientation over the eggs. Each vaccinator is manufactured for one particular size and type of egg flat. Because eggs vary greatly in size, many hatcheries have two or more types of incubator egg flats with different configurations for larger and smaller sized eggs. In these hatcheries, the use of the device of the '979 patent requires a separate vaccinator machine for each type and size of egg flat.
Finally, contamination is a very major concern and must be controlled since any contaminant entering the hole made by the injector has the potential to kill the embryo. The device of the '979 patent has two plates fixed to one another and it is extremely difficult to sanitize the joints between the two plates.